umm... im not sure of a shop as such.
I have heard of a guy who builds MB's. you buy them and ship them to his house. And he builds you, what you give him for about $100 bucks or so.
I got my china stuff from "MBB imports" in seednee.
have a look in a oztraya laws in http://motorbicycling.com/showthread.php?t=39266
remember there is no limit on engine size, just power output
there is stuff from the RTA in there.